1. Field of the Invention
The present invention relates to heat sink fasteners, and more particularly to a heat sink fastener which easily and firmly fastens a heat sink to an electronic package.
2. Description of Prior Art
With the rapid development of electronics technology, electronic packages such as CPUs are able to process signals at unprecedented high speeds. As a result, CPUs can generate copious amounts of heat. The heat must be efficiently removed from the CPU. Otherwise, abnormal operation or damage may result.
Conventionally, a fastener secures a heat sink on a CPU to remove heat therefrom. A common fastener is integrally formed and substantially M-shaped to provide the fastener with resiliency. However, the fastener has some shortcomings. If the fastener is too weak, the heat sink cannot be firmly and reliably secured to the CPU. If the fastener is too strong, one or more additional tools are required for securing and detachment of the heat sink. Any additional tools render these procedures unduly laborious.
To overcome the shortcomings of the above-mentioned integrally formed fasteners, multiple piece fasteners have been developed. U.S. Pat. No. 5,638,258 discloses a multiple piece fastener. Referring to FIG. 7, the fastener comprises a pressure bar 1, an actuating lever 2, and a clamping bar 3. One end of the pressure bar 1 is fastened to one side of a CPU mounting module. The actuating lever 2 is pivotably attached to an opposite end of the pressure bar 1. The clamping bar 3 is pivotably attached to the actuating lever 2, and one end of the clamping bar 3 is fastened to an opposite side of the CPU mounting module. When the actuating lever 2 is rotated up toward the pressure bar 1, the fastener is secured to the CPU mounting module. The pressure bar 1 resiliently presses the heat sink on the CPU. When the actuating lever 2 is rotated up away from the pressure bar 1, the fastener is released from engagement with the CPU mounting module.
The above-described multiple piece fastener overcomes certain of the shortcomings of integrally formed fasteners. However, the actuating lever 2 is not fixed, and is prone to be displaced when the fastener is subjected to vibration or shock during normal use. Displacement of the actuating lever 2 can cause the pressure bar 1 and the clamping bar 3 to be released from resilient engagement with the CPU mounting module.
Accordingly, an object of the present invention is to provide a heat sink fastener which easily and firmly fastens a heat sink to an electronic package.
In order to achieve the object set out above, a heat sink fastener in accordance with a preferred embodiment of the present invention comprises a pressing beam, a clamping beam and an operating lever. The pressing beam includes a first pivot portion at one end thereof, and a hook at an opposite end thereof. The clamping beam has a second pivot portion at a top end thereof, and a hook at a bottom end thereof. The operating lever is pivotally engaged with each of the first and second pivot portions. The operating lever includes a pair of parallel pivot plates, each forming a protrusion on an internal face thereof. In use of the fastener, the fastener is unlocked when the protrusions and the clamping beam are disposed at a same side of the first pivot portion. The operating lever is pressed to move the fastener from the unlocked position to a locked position. The fastener is thus locked when the protrusions and the clamping beam are disposed at opposite sides of the first pivot portion. In this position, the protrusions are blocked by the first pivot portion from moving back toward their original positions. That is, the protrusions lock the operating lever in position. Thus, a heat sink can be easily and securely attached on an electronic package by, say, a pair of the fasteners in the exemplary application disclosed.
Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: